Octopus-inspired Eight-arm Robotic Swimming by Sculling Movements

Conference PaperinProceedings - IEEE International Conference on Robotics and Automation · May 2013with103 Reads
DOI: 10.1109/ICRA.2013.6631314
Conference: IEEE Int. Conf. Rob. Autom. (ICRA'13), Volume: pp. 5135-5141
Abstract
Inspired by the octopus arm morphology and exploiting recordings of swimming octopus, we investigate the propulsive capabilities of an 8-arm robotic system under various swimming gaits, including arm sculling and arm undulations, for the generation of forward propulsion. A dynamical model of the robotic system, that considers fluid drag contributions accurately evaluated by CFD methods, was used to study the effects of various kinematic parameters on propulsion. Exper- iments inside a water tank with an 8-arm robotic prototype successfully demonstrated the sculling-only gaits, attaining a maximum speed of approximately 0.2 body lengths per second. Similar trends were observed, as in the simulation studies, with respect to the effect of the kinematic parameters on propulsion.
    • "A second cyclic motion was investigated, termed as sculling [4,52,37,38], by adopting the motion profile ofFig. 2b. "
    [Show abstract] [Hide abstract] ABSTRACT: The complexity in structure and locomotion of cephalopods, such as the octopus, poses difficulties in modeling and simulation. Their slender arms, being highly agile and dexterous, often involve intense deformations, which are hard to simulate accurately, while simultaneously ensuring numerical stability and low diffusion of the transient motion results. Within the immersed-boundary framework, this paper focuses on an arm geometry performing prescribed motions that reflect octopus locomotion. The method is compared with a finite-volume numerical approach to determine the mesh requirements that must be employed for sufficiently capturing, not only the near wall viscous flow, but also the off-body vortical flow field in intense forced motions. The objective is to demonstrate and exploit the generality of the immersed boundary approach to complex numerical simulations of deforming geometries. Incorporation of arm deformation was found to increase the output thrust of a single-arm system. It was further found that sculling motion combined with arm undulations provides an effective propulsive scheme for an octopus-like arm.
    Full-text · Article · Jul 2015
    • "When limbs move without contacting the ground, the passive silicone part performs sculling movements. Several studies have been conducted on conical silicone arms [43, 50] performing rotational movements (while in our case the arms rotate and translate, due to the three-bar mechanism). In these works the contribution of the hydrodynamic forces (normal and tangential to the arm axis) was derived along the whole arm, and the greater contribution was found to be in the proximal part of the silicone cone. "
    [Show abstract] [Hide abstract] ABSTRACT: This paper studies underwater legged locomotion (ULL) by means of a robotic octopus-inspired prototype and its associated model. Two different types of propulsive actions are embedded into the robot model: reaction forces due to leg contact with the ground and hydrodynamic forces such as the drag arising from the sculling motion of the legs. Dynamic parameters of the model are estimated by means of evolutionary techniques and subsequently the model is exploited to highlight some distinctive features of ULL. Specifically, the separation between the center of buoyancy (CoB)/center of mass and density affect the stability and speed of the robot, whereas the sculling movements contribute to propelling the robot even when its legs are detached from the ground. The relevance of these effects is demonstrated through robotic experiments and model simulations; moreover, by slightly changing the position of the CoB in the presence of the same feed-forward activation, a number of different behaviors (i.e. forward and backward locomotion at different speeds) are achieved.
    Full-text · Article · Jul 2015
    • "Although this captures the basic motion components, a more quantified kinematic description would reveal new aspects of this unique propulsion mode if implemented in robotic models. We have recently presented a multi-arm underwater robot [11]–[14] that mimics the morphology of the octopus, possessing 8 compliant arms and a passively-compliant web. The robotic model has included detailed information of hydrodynamic results [15]–[18] and is in accordance with relevant elastodynamic investigations of arm muscle acti- vation [19], [20]. "
    [Show abstract] [Hide abstract] ABSTRACT: The octopus uses the arm-swimming behavior primarily for escape, defense, or foraging. This mode of locomotion is comprised of two strokes, with the arms opening slowly and closing rapidly, and generally results in considerable propulsive acceleration. In light of the recent development by our group of an octopus-like eight-arm underwater robot, we are interested to analyze the details of the biological arm swimming motion, in order to understand its kinematics. In this paper, we address methodological aspects of the 3D reconstruction process of octopus arm trajectories, based on computer vision, and present the resulting arm swimming movement of a benthic common octopus. The 3D trajectories of all eight octopus arms were tracked and analyzed, providing information about speed, acceleration and arm elongation. The animal's performance is then used for a direct comparison with our 8-arm robotic swimmer. The data obtained provide new kinematic information about this, relatively unknown, propulsive mode, which can be exploited for multi-functional underwater robots.
    Full-text · Article · Jun 2015
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